FIX: CComQIPtr operator= Causes an Access Violation

ID: Q174891

The information in this article applies to:

The Microsoft Active Template Library (ATL), versions 2.0, 2.1

SYMPTOMS

When a CComQIPtr is assigned a NULL pointer, an access violation occurs.

CAUSE

When a CComQIPtr is assigned a NULL pointer, no check is done, and a QueryInterface is attempted with the NULL pointer. This behavior causes the access violation.

RESOLUTION

Do not assign NULL pointer to a CComQIPtr object.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug has been fixed in Visual Studio 97 Service Pack 3.

For more information, please see the following article in the Microsoft Knowledge Base:

Q170365 INFO: Visual Studio 97 Service Packs - What, Where, and Why

MORE INFORMATION

Steps to Reproduce Behavior


   CComQIPtr<IMyInterface, IID_IMyInterface> ptr;
   IUnknown* pUnk = NULL;
   ptr = pUnk;

Additional query words:

Keywords : kbATL200bug kbATL210bug kbCOMt kbVS97sp2fix kbATL300fix kbGrpMFCATL kbArchitecture
Version : WINDOWS:2.0,2.1
Platform : WINDOWS
Issue type : kbbug